*This is an abstract only. No full paper is available for this abstract.* Over the last 30 years, the average feed grade of Australian base and precious metal mining operations has halved while waste removed to access ore has more than doubled. This reflects the geological nature and capital scaling of bulk tonnage mining operations. While continuous improvement in extractive technologies together with high commodity prices have facilitated profitable extraction of bulk low-grade ores, overall productivity and return on investment have shown marked declines. This underlying frailty in productivity has now been exposed by falling commodity prices. Increased material movement and higher processing throughput have been the typical response to maintain revenue during lower commodity price cycles._x000D_
The development of grade engineering recognises there are other operational strategies and technologies that can be used to avoid over-reliance on throughput maximisation at the expense of grade. The ultimate aim of grade engineering is to improve life-of-mine unit metal productivity. This involves a range of integrated technologies and circuit designs for improving effective feed grades based around early rejection of gangue and waste dilution before energy-intensive processing operations such as grinding._x000D_
Key rock-based drivers for effective grade engineering application include exploitation of in situ grade variability at scales smaller than the minimum mining unit through differential blasting and screening; use of preferential grade by size deportment responses to increase grade in specific size fractions; and implementation of sensor-based sorting either at particulate stream level following screening, or run-of-mine feed belt scale._x000D_
Examples will be presented of site application studies showing the magnitude and operational implications of these rock-based drivers and typical response variability within mineralised systems. Variable responses need to be embedded within resource block models as additional geometallurgical-type predictive attributes. The ability to generate multiple accept-and-reject grade streams on an intra-block basis represents a major cultural and operational challenge for dynamic cut-off grade optimisation linked to productivity and not simply production._x000D_
CITATION: Bye, A and Walters, S, 2014. Application of grade engineering to exploit mineralisation variability and deliver improved life-of-mine productivity, in Proceedings Ninth International Mining Geology Conference 2014, pp 3-4 (The Australasian Institute of Mining and Metallurgy: Melbourne).